Scoreboard UI and team selection

Scoreboard UI (TAB-ESC to enter) with keyboard interface:

• (SHIFT+)TAB to select a panel
  • Rankings panel
    • LEFT/RIGHT to show rankings not fitting in the compressed Rankings panel
  • Scoreboard:
    • SPACE/ENTER (or SHIFT+SPACE/ENTER) to join the game (enters team selection mode in team games)
    • CTRL-C to change default / all / custom columns layout.
    • UP/DOWN arrow to select a player
      • SPACE/ENTER to spectate him
      • CTRL-K to kick him
      • CTRL-T to send him a private message (tell)

Team selection mode (F5 to enter) replaces the team selection menu:

• (SHIFT+)TAB or UP/DOWN arrow to select a team
• SPACE/ENTER to auto-select a team and join if no team is selected (default), otherwise it joins the selected team
• can't be opened when the game is over

Extra:

• Rankings panel: display rankings not fitting in the compressed rankings panel after a few seconds
• Reduce team selection command spam when team selection is enabled by the server (i.e. not enabled manually with F5)